A numerical study on the fatigue and rolling contact fatigue behaviour of PVD-coated steel and titanium spur gears

Thin hard coatings deposited with physical vapor deposition (PVD) can enhance both the fatigue and the rolling contact fatigue resistance of mechanical components. In this work a cheap and fast way to evaluate the best parameter levels of coating and bulk material is proposed. Design of Experiments (DoE) was applied to the numerical results obtained from the simulation of meshing PVD-coated spur gears. Preliminary analyses were performed to assess the fatigue behaviour of PVD-coated standard specimens for rotating bending tests. The coating elastic modulus and thickness, and the trend of the residual stresses induced by the deposition process were considered among the variables affecting the fatigue and the rolling contact fatigue behaviour. Different bulk materials, including steel and titanium alloys, were analyzed. The proposed method may help to define the optimal coating design, especially when the replacement of traditional steels with light alloys constitutes a goal that is strongly recommended.